Are the motors on your mini quad getting very hot after flight and you are wondering what’s causing it? Here are some tips to troubleshoot motor overheating issues.
It’s normal that motors on a mini quad get warm after a flight, because they can spin up to a few hundreds times per second. But you might have a problem if they get too hot.
So how hot is too hot?
An easy way to tell is to pinch the motor by the bell with your fingertips, ideally right after landing. If you can hold your fingers there for more than 10 seconds comfortably, then it’s fine. If it’s too hot to hold, then it’s definitely a sign of overheating motor.
Your motors will get hot after some aggressive flying. To properly diagnose the issue you should fly slowly – 40% to 70% throttle is a good range, and one or two flips and rolls here and there are fine.
With hot motors, the very first thing I’d check would be if your motor screws are touching the windings.
PID and Filter tuning in Betaflight can be a rabbit hole. If you are getting hot motors after changing PID and filter settings in Betaflight, you should reset these settings back to default.
Default settings in Betaflight is known to be conservative and generally pretty good to avoid oscillations and hot motors. Once you’ve made sure you don’t get hot motors anymore, you can start tuning it more aggressively, one setting at a time. Common things to pay attention to are:
If you are still getting hot motors with default PID and filter settings, then that’s an indication that the problem might be mechanical.
Something might be wrong with hardware, keep reading for more tips on troubleshooting.
Maybe something isn’t done properly with the build.
If you are not soft-mounting the FC, then you should! As long as you are soft mounting the FC properly, you don’t need to worry about soft mounting the motors.
Adding extra capacitors to the ESC power or XT60 pads, will help reduce the amount of noise in your power. Thus reducing the noise in the gyro data too!
If two of the motors are hotter than the others, it could be caused by unbalanced weight distribution. If your quad is front heavy, or tail heavy, two of the motors will have to work harder and therefore get hotter. Make sure the COG is right in the center for the best possible performance.
Make sure the propellers are not hitting anything on your frame (battery strap, zip tie, standoffs etc), and that the motors are not getting jammed by dirt or grass… If this is the case you should usually hear it when the motors are spinning.
Also make sure the props are not bent. It’s quite hard to tell visually sometimes, change them out if in doubt.
It’s possible that you have one or multiple faulty motors. Maybe the bearing is bad, or the motor bell is scraping the stator due to bent shaft, or a unbalanced motor bell…
If you have one motor that is hotter than the rest, and nothing mentioned above helped, try swapping around the problematic motor with a fine motor on the same quad, see if that’s still the issue with that motor.
Take into account the ambient temperature outside, your motors will have a harder to time to cool down on a hot day. Black motors will be affected even more when you are flying under the sun.
If this is the case, try again under the shade or in the evening.